Of course it depends on what professor you get, but the general consensus on my day (and from others I know that interviewed there) are that they are quite laid back and more conversational than the typical "Q & A" session. There's probably plenty of info on this in the med school interview info section, if you haven't already checked it out.
Also, it's closed file, which means they don't see any of your numbers. When I interviewed, she just saw the courses I took, without the grades and my AMCAS personal statement, which I handed to her directly before my interview. She preferred to read that after my interview.
The NYMC interview is not one to worry about - I enjoyed my visit.